In order to distribute important system parameters required by user equipment UE (also known as mobile stations or subscribers) for it to properly access the system, the network broadcasts these parameters in information blocks. The information sent by the network to the UE concerns parameters involved in cell selection and reselection, measurement management, location and routing registration, handover, power controls, etc. One master information block (MIB) and a number of system information blocks (SIBs) are defined by 3GPP in document 3GPP TS 25.331.
All blocks are broadcast over the air interface via a Broadcast Control Channel (BCCH) (BCH). Broadcast Control Channel (BCCH) is a logical channel and a Broadcast Channel (BCH) is a transport channel. BCCH is mapped to BCH. A MIB gives references and scheduling information to a number of system information blocks in a cell. The master information block may also contain references to a scheduling block (SB) which contains scheduling information related to additional system information blocks in the cell as illustrated in FIG. 1. The scheduling information helps the user equipment to find and read the referred SIB or SB.
The system information blocks contain the actual system information applicable for different WCDMA RAN (Wideband Code Division Multiple Access Radio Access Network) functionalities. System information is broadcast to user equipment in a series of system information blocks. A SIB groups together system information elements of the same nature. Different SIBs may have different characteristics and rules of their transmissions e.g. regarding their repetition rate, initial position on a transport channel and the requirements on UEs to re-read the system information blocks. The SIBs contain all information necessary for UEs to work properly in both idle and connected mode.
The main disadvantage of this known solution is that all UEs in one cell (also known as mobile stations or subscribers) receive exactly the same information (i.e. system parameters) and some of them receive information they do not need, whereas some do not receive information they need.